How to update a value with substring of current value by removing the separator and numbers after a separator in MySQL?

Here, let’s say you have a string with form “StringSeparatorNumber” form like John/56989. Now if you want to remove the number after separator /, then use the SUBSTRING_INDEX(). Let us first create a table −

mysql> create table DemoTable
(
   StudentName varchar(100)
);
Query OK, 0 rows affected (1.05 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values('John/56989');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable values('Carol');
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable values('David/74674');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values('Bob/45565');
Query OK, 1 row affected (0.09 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+-------------+
| StudentName |
+-------------+
| John/56989  |
| Carol       |
| David/74674 |
| Bob/45565   |
+-------------+
4 rows in set (0.00 sec)

Following is the query to update a value with substring of current value −

mysql> update DemoTable set StudentName=substring_index(StudentName,'/',1);
Query OK, 3 rows affected (0.13 sec)
Rows matched :4 Changed :3 Warnings :0

Let us check the table records once again −

mysql> select *from DemoTable;

This will produce the following output −

+-------------+
| StudentName |
+-------------+
| John        |
| Carol       |
| David       |
| Bob         |
+-------------+
4 rows in set (0.00 sec)